Air cylinder with hydraulic control



Feb 7, T

AIR CYLINDER WITH HYDRAULIC CONTROL 3. F. HUTTER Filed June 14, 1965 (iiNY 1 NOR mew inf/221a @WMMJ we (A1044 United States Patent 3,302,533 AIRCYLWDER WITH HYDRAULIC CONTROL James F. Hutter and Leonard Kelly,Peterborough, On-

tario, Canada, assignors to Sphere investments Limited, Nassau, BahamaIslands Filed June 14, 1965, Ser. No. 463,829 5 Claims. (Cl. 928) Thisinvention relates to fluid power actuators and more particularly tohydraulically controlled air legs and cylinders.

Various types of hydraulically controlled air legs and cylinders aredisclosed in our prior Patents Numbers 3,146,680, issued September 1,1964 and 3,149,541, issued September 22, 1964, and the present inventionis directed to a cylinder assembly of generally similar type butconsiderably modified form.

The present invention contemplates the provision of a low cost,doubleacting, air-powered cylinder having an internal, self-contained,pre-set hydraulic control means. Such a cylinder is useful in manyapplications including the operational control of doors, loading chutes,jigs and fixtures, drill feeds, and the like.

The air cylinder in accordance with the invention comprises a maincylinder, a hollow push rod extending axially into the main cylinder andan air piston fixed to the push rod in the cylinder and providing a rearair chamber on one side thereof and a forward air chamber on the otherside thereof. A hydraulic controlled cartridge is removably mounted inthe push rod and comprises a tube having an external diameter less thanthe internal diameter of the push rod to provide an annular air passagebetween the tube and the push rod. A hydraulic piston rod is fixed tothe main cylinder and extends through the air piston into the tube. Ahydraulic piston assembly is mounted on the hydraulic piston rod in thetube and provides a rear oil chamber on one side thereof and a forwardoil chamber on the other side thereof. The piston assembly has an oilflow passage from one of the oil chambers to the other and means areprovided for controlling oil flow through such passage. A cover isslidably mounted in the tube adjacent each end thereof and closes arespective one of the oil chambers, one of the covers being exposed toair in the forward air chamber and the other of the covers being exposedto air in the rear air chamber. The air piston rod has a portcommunicating with the forward air chamber and the annular air passageand each of the forward and rear air chambers has an air inlet andoutlet port.

The invention will be described with reference to the accompanyingdrawing, in which the single figure is a sectional side elevation of acylinder assembly in accordance with the invention.

In the drawing, is the main tube or cylinder which is provided at oneend with a blind end cap 11 and at the other end with a gland cap 12. Ahollow push rod or air piston rod 13 extends through the gland cap intothe cylinder and has fixed to its inner end an air piston 14. A closurecap 15 with suitable coupling means 15a is mounted on the outer end ofthe rod 13. As shown, the piston is provided with packer rings 16. Thepiston forms in the cylinder a forward air chamber 17, having a passage18 in gland 'cap 12 and a port 19, and a rearward air chamber 20 havinga passage 21 in cap 11 and port 22.

Located within the piston rod 13 is a removable hydraulic cartridge 23comprising a tube 24 each end of which terminates inwardly of theadjoining end of rod 13. The external diameter of the tube 24 is lessthan the internal diameter of rod 13 to provide a space 25 between theopposed wall surfaces of rod 13 and tube 24. As shown, the radial extentof space 25 may be relatively small.

The inner end of tube 24 is provided with a cap 26 hav- 3,392,533Patented Feb. 7, 1967 ing a portion extending into the tube and aport-ion extending into an axial bore 27 in the piston.

The outer end of tube 24 is closed by a floating cover 28 which isslidably mounted in the tube. Sealing engagement with the tube wall isprovided by an O-ring 29. As shown, the cover 28 has an axial air bleedbore 311 closed by a cap 31. The space 32 in the piston rod between caps15 and 31 communicates with the air chamber 17 through the annular space25 and port 32a.

A hydraulic piston rod 33 has one end removably fixed to blind end cap11 and extends axially into piston rod 13 and tube 24. The rod 33extends through an axial bore 34 in cap 26, the wall of the bore beingslightly spaced from the rod to form an annular space 35 therebetweenwhich communicates with an inner space 36 within the tube 24 andproviding communication between space 36 and air chamber 20.

Mounted on the free end of piston rod 33 is a piston or metering valveassembly 37 incorporatingvalve means operable during the extension andretraction strokes of the piston rod 13. The assembly 37 comprises aretraction valve member 38 and an extension valve member 39, each in theform of a collar or annulus fixed to rod 33, and a tubular valve seatmember 44) freely reciprocal between members 38 and 39. Seat member 40has an axial fluid flow passage 41 therein and has sealing engagement,as by O-ring 42, with tube 24. Seat member 40 has, as shown, a bevelledseat 43 at one end for engagement with a complementary seat 44 onretraction member 38 and a bevelled seat 45 at its other end forengagement with a complementary seat 46 on member 39. Member 38 has apair of slots or passages 47 in the seat thereof which providesthrottled fluid flow therethrough during the extension stroke, i.e.,when member 40 is seated on member 38. Member 39 has a pair of slots orpassages 48 in the seat thereof for fluid flow therethrough during theretraction stroke, i.e., when member 50 is seated on member 39.

Assembly 37 provides within tube 24 a low pressure oil reservoir 49between assembly 37 and floating cover 28 and a high pressure oilreservoir 50 between assembly 37 and a second floating cover 51 havingsealing engagement with the inner wall of tube 24 and with piston rod33.

In operation, the free space between floating covers 28 and 51 in tube24 is provided with a body of oil.

To perform an extension stroke, air under pressure is supplied tochamber 20 through port 22 and the push rod 13 extends. Oil underpressure in reservoir 50 is metered through orifice 48 into reservoir49, the forward speed of the push rod 13 being controlled or limited bythe size of orifice 48.

When the extension stroke is completed, residual air pressure throughspaces 35, 36 continues to act on floating cover 51 to transfer oil tolow pressure reservoir 49 and to move floating cover 28 ahead until itstops against the closure cap 15. The space between assembly 37 andcover 28 is now full of oil preparatory to a retraction stroke.

To perform a retraction stroke, air under pressure is supplied tochamber 17 through port 19 and the push rod retracts. Oil under pressurefrom reservoir 49 is metered through orifice 47 into reservoir 50, therearward speed of the push rod being controlled or limited by the sizeof orifice 47. When the retraction stroke is complete, transfer of oilfrom reservoir 49 to reservoir 50 will continue until the floating cover51 engages cap 26. An extension stroke may then be started.

The hydraulic control cartridge 23 is readily insertable in andremovable from the assembly. The cartridge is a self-contained unitwhich is pre-set to accomplish its desired control function. Thus, thesize of the orifices 47 and 48 may be chosen to perform the desireddegree of control for any particular operation.

Since the cartridge is a self-contained unit, its replacement asrequired is a simple operation.

We claim:

1. A hydraulically controlled air cylinder comprising a main cylinder, ahollow push rod extending axially into said cylinder, an air pistonfixed to said push rod in said cylinder and providing a rear air chamberon one side of said air piston and a forward air chamber on the otherside of said air piston, a hydraulic control cartridge in said push rodcomprising a tube having an external diameter less than the internaldiameter of said push rod to provide an annular air passage between saidtube and push rod, a hydraulic piston rod fixed to and axially arrangedin said cylinder, said hydraulic piston rod extending through said airpiston, a hydraulic piston assembly mounted on said hydraulic piston rodin said tube and providing a rear oil chamber on one side of said pistonassembly and a forward oil chamber on the other side of said pistonassembly, means providing an oil flow passage through said pistonassembly from one of said oil chambers to the other, means controllingoil flow through said oil flow passage, and a cover slidably mounted insaid tube adjacent each end thereof and closing a respective one of saidoil chambers, a first one of said cover-s being exposed to air in saidforwardair chamber and a second one of said covers being exposed to airin said rear air chamber, said covers having floating movement in saidtube in response to differential fluid pressures thereon, said airpiston rod having a port communicating with said forward air chamber andsaid annular air passage, means providing an air inlet and outlet portcommunicating with said forward air chamber, and means providing an airinlet and outlet port communicating with said rear air chamber.

2. A hydraulically controlled air cylinder as defined in claim 1, saidmain cylinder having a blind end cap closing one end thereof and a glandcap closing the other end thereof and through which said air piston rodextends, each of said caps having one of said air inlet and outlet portstherein.

3. A hydraulically controlled air cylinder as defined in claim 2, saidhydraulic piston rod being removably fixed to said blind end cap.

4. A hydraulically controlled air cylinder as defined in claim 1, saidhydraulic piston assembly comprising a pair of spaced annular membersfixed to said hydraulic piston rod, each said annular member having avalve seat, said valve seats being in confronting relation, each saidvalve seat having an oil metering passage therein, and a tubular valveseat member between said valve seats and freely reciprocal intoengagement with each one of said valve seats.

5. A hydraulically controlled air cylinder as defined in claim 1, saidtube having an annular closure member fixed to an end thereof adjacentsaid second cover, said closure member having an axial-bore permittingpassage therethrough of said hydraulic piston rod and exposing saidsecond cover to air in said rear air chamber.

References Cited by the Examiner UNITED STATES PATENTS 2,746,557 5/1956Augustin 92-8 X 3,146,680 9/1964 Hutter et a1. 92l2 3,149,541 9/ 1964Hutter et a1. 928 X MARTIN P. SCHWADRON, Primary Examiner. I. C. COHEN,Assistant Examiner.

1. A HYDRAULICALLY CONTROLLED AIR CYLINDER COMPRISING A MAIN CYLINDER, AHOLLOW PUSH ROD EXTENDING AXIALLY INTO SAID CYLINDER, AN AIR PISTONFIXED TO SAID PUSH ROD IN SAID CYLINDER AND PROVIDING A REAR AIR CHAMBERON ONE SIDE OF SAID AIR PISTON AND A FORWARD AIR CHAMBER ON THE OTHERSIDE OF SAID AIR PISTON, A HYDRAULIC CONTROL CARTRIDGE IN SAID PUSH RODCOMPRISING A TUBE HAVING AN EXTERNAL DIAMETER LESS THAN THE INTERNALDIAMETER OF SAID PUSH ROD TO PROVIDE AN ANNULAR AIR PASSAGE BETWEEN SAIDTUBE AND PUSH ROD, A HYDRAULIC PISTON ROD FIXED TO AND AXIALLY ARRANGEDIN SAID CYLINDER, SAID HYDRAULIC PISTON ROD EXTENDING THROUGH SAID AIRPISTON, A HYDRAULIC PISTON ASSEMBLY MOUNTED ON SAID HYDRAULIC PISTON RODIN SAID TUBE ABD PROVIDING A REAR OIL CHAMBER ON ONE SIDE OF SAID PISTONASSEMBLY AND A FORWARD OIL CHAMBER ON THE OTHER SIDE OF SAID PISTONASSEMBLY, MEANS PROVIDING AN OIL FLOW PASSAGE THROUGH SAID PISTONASSEMBLY FROM ONE OF SAID OIL CHAMBERS TO THE OTHER, MEANS CONTROLLINGOIL FLOW THROUGH SAID OIL FLOW PASSAGE, AND A COVER SLIDABLY MOUNTED INSAID TUBE ADJACENT EACH END THEREOF AND CLOSING A RESPECTIVE ONE OF SAIDOIL CHAMBERS, A FIRST ONE OF SAID COVERS BEING EXPOSED TO AIR IN SAIDFORWARD AIR CHAMBER AND A SECOND ONE OF SAID COVERS BEING EXPOSED TO AIRIN SAID REAR AIR CHAMBER, SAID COVERS HAVING FLOATING MOVEMENT IN SAIDTUBE IN RESPONSE TO DIFFERENTIAL FLUID PRESSURES THEREON, SAID AIRPISTON ROD HAVING A PORT COMMUNICATING WITH SAID FORWARD AIR CHAMBER ANDSAID ANNULAR AIR PASSAGE, MEANS PROVIDING AN AIR INLET AND OUTLET PORTCOMMUNICATING WITH SAID FORWARD AIR CHAMBER, AND MEANS PROVIDING AN AIRINLET AND OUTLET PORT COMMUNICATING WITH SAID REAR AIR CHAMBER.